Penta-azaindene compounds useful as stabilizers against fog for silver halide photographic materials



United States atent O 3,398,148 PENTA-AZAINDENE COMPOUNDS USEFUL AS STABILIZERS AGAINST FOG FOR SILVER HA- LIDE PHOTOGRAPHIC MATERIALS Douglas .Iames Fry and Patrick Joseph Keogh, Ilford,

Essex, England, assignors to Ilford Limited, Essex, England, a British company No Drawing. Original application Dec. 30, 1963, Ser. No. 334,644, now Patent No. 3,333,961, dated Aug. 1, 1967. Divided and this application Dec. 16, 1966, Ser. No.

17 Claims. (Cl. 260-2495) ABSTRACT OF THE DISCLOSURE A new class of chemical compounds, penta-azaindene compounds of the general Formula II:

where R is a hydrogen atom or an alkyl, aryl, aralkyl, mercapto, alkylthio, or aralkylthio group, and R is a hydrogen atom or an alkyl, aryl, aralkyl, or alkoxycarbonyl group, with the exception of the case where, simultaneously, R is a hydrogen atom and R is a methyl group. The compounds are useful as stabilizing agents against fog for silver halide photographic emulsions.

Disclosure This is a division of our copending application Ser. No. 334,644, filed Dec. 30, 1963.

This invention relates to heterocyclic compounds, more particularly penta-azaindene compounds, to their production and to their use as stabilizing agents for photographic emulsions.

The parent penta-azaindene is positionally numbered as follows:

() CH N CH N According to the present invention there are provided, as a new class of chemical compounds, penta-azaindene compounds of the general Formula II:

fl- NHNH:

where R has the meaning assigned to it above with carbon disulphide in alcoholic solution in the presence of a strong organic base, e.g. triethylamine, or an alkali metal hydroxide, e.g., sodium ethoxide, until hydrogen sulphide is no longer evolved, thereby to produce a compound of general Formula II in which R is mercapto.

(b) By reacting a mercapto compound as produced by method (a) with an alkylating or aralkylating agent in neutral or alkaline solution, thereby to produce a compound of general Formula II where R is alkylthio or aralkylthio.

(c) By reacting a triazole of general Formula IV:

i R1C/ \(IDNH2 wherein R has the meaning assigned to it above with an on keto acid or ester of general Formula V:

R2COCOOR3 wherein R has the meaning assigned to it above and R is a hydrogen atom or an alkyl group.

(d) By treating the corresponding mercapto compound where R is mercapto or alkylthio or aralkylthio with Raney nickel catalyst containing adsorbed hydrogen, thereby to produce a corresponding compound wherein R is hydrogen.

(e) By ring closure of compounds of general Formula R /N\N ll C-NHNHOOR:

HO N W where R has the meaning assigned to it above, thereby to produce compounds where R is a hydrogen atom, or an alkyl aryl or aralkyl group. This ring closure may be effected by treating the compound just above its melting point or by heating with an acid, preferably by heating with an acid of the formula R COOH.

The compounds of this invention, and the compound where R =H and R =CH have been found to be valuable stabilizing agents for photographic silver halide emulsions. Only very small quantities of the compounds are necessary to stabilize the emulsions against development of fog. For example, a range of quantities of 0.02 to 1 gm. for an emulsion containing 1% g.-mols silver halide, e.g., iodobromide, is typically sufficient.

The following examples will serve to illustrate the invention:

EXAMPLE 1 Preparation of 5-methyl-6-hydroxy-1,2,3a,4,7-pentaazaindene This compound was prepared according to the method described by Fusco and Rossi, Rend. Inst. Lom. 88, 184 (1955), (CA. 50, 10743a).

3 hydrazino-S-hydroxy-6-methyl-1,2,4 triazine (16.0 g.) in formic acid (160 ml. of w./w.) and water (20 ml.) was refluxed for 2 /2 hrs. After evaporating down under vacuum almost to dryness, ethanol ml.) was added and the product (13 g.) filtered off; two crystallization from ethanol (1% liters and 1 liter), yielded colorless flakes (9.5 g.), M. Pt. 274-275.

The same compound was obtained when 3,4-diamino- 1,2,4-triazole (10 g.) and ethyl pyruvate (12.3 ml.) were reacted together in glacial acetic acid (50 ml.) for 2 /2 hours. The reaction mixture was poured into cold ethanol (500 ml.) and the precipitate collected (10.5 g.). Recrystallization from ethanol (1 liter) yielded colorless flakes, 7 g., M. PL, 274-275.

The same compound was also prepared by the following procedure:

A solution of 6 hydroxy 3 mercapto-S-methyl- 1,2,3a,4,7-penta-azaindene g.) in ammonium hydroxide ml. of s.g. 0.920) and water ml.) was refluxed for 1 hour with Raney nickel g.) by which time the initial deep yellow color had faded. The solids were then removed by filtration and the filtrate, after acidification, was evaporated to half volume and cooled. Colorless plates (2.2 g.) were obtained.

The infrared absorption spectra of all three products showed them to be identical. The 3,4-diamino1,2,4,- triazole was prepared from N.N.'-diaminoguanidine hydriodide and formic acid (cf. Gaiter, Gazz. Chim. Ital. 45, I. 457 (1915)).

The product was added to silver iodobromide emulsion at the rate of 0.5 g. per 1 mols silver halide and the emulsion coated on a support. A control coating was made with emulsion not containing the product. Specimens of the control and test coatings were tested for fog density and speed immediately after coating. Further specimens were stored in a sealed container for 14 days at 120 F. and 56% relative humidity, and the tests for speed and fog density repeated. The folowing table shows the results obtained:

Initial Test After 14 days at 120 F.

Fog density Rel. log speed Fog density Rel. log speed Preparation of 6-hydroxy-3-mercapto-5-methyl-1,2,3a,4,7- penta-azaindene A mixture of 3-hydrazino-5-hydroxy-6-methyl-l,2,4- triazine (16 g.), carbon disulphide (8.6 g.), triethylamine (33 g.) in methanol (500 ml.) was refluxed for 16 hours by which time hydrogen sulphide had ceased to be evolved: the solution was then evaporated under vacuum to dryness. The residue was dissovled in water (200 m1.) and acidified with concentrated hydorchloric acid (20 ml.), on cooling, the crude material crystallized and was filtered off and recrystallized three times from wa1er to yield yellow needles (4.5 g. from 120 ml. water), M. Pt. 3103l5, with evolution of hydrogen sulphide and resolidification.

The same compound was obtained when 3,4-diamino- S-mercapto-1,2,4-triazole (4. g.) and ethyl pyruvate (4 ml.) were reacted together in refluxing acetic acid (70 ml.). On refluxing for 1 hr. the triazole gradually dissolved and the product crystallized out. The product was filtered off after cooling and recrystallized with water to give transparent yellow needles (2.2 g.), M. Pt. 310 315, with evolution of hydrogen sulphide and resolidification.

The same product was also prepared as follows:

Sodium (2.2 g.) was dissolved in ethanol (200 ml.) and to the resulting solution 3-hydraZino-5-hydroxy-6- methyl-1,2,4-triazine 15 g.) and carbon disulphide (10 ml.) were added. The mixture was refluxed for 3 hours, during which time hydrogen sulphide was evolved and a crystalline solid formed. After cooling, the mixture was filtered to yield solid and filtrate. The solid was dissolved in water and the resulting solution acidified with concentrated hydrochloric acid, whereupon the product was obtained as a yellow precipitate. This was filtered 01f and recrystallized from water as yellow needles, M. Pt. 310 315 C., with evolution of hydrogen sulphide and resolidification.

The infrared absorption spectra of all three products were identical. The 3,4-diamino-5-mercapto-1,2,6-triazole was prepared from bisthiourea and hydrazine hydrate as described by Hoggarth, J. Chem. Soc, 1952. 4818.

The product was tested in the same way as the product of Example 1. The following table shows the results obtained using 0.1 g. of product per 1 /2. mols silver iodobromide.

Initial Test After 14 daysat F.

Fog density Rel. log speed Fog density Rel. log speed Preparation of 6-hydroxy-3-methylthio-5-methyl- 1,2,3a,4,7-penta-azaindene 6 hydroxy 3-mercapto-5-methyl-1,2,3a,4,7,-pentaazaindene (3. g.) was dissolved in methanol (75 ml.) and water (25 ml.) and methyl iodide (12.5 ml.) added. After refluxing for 4 hours some of the solvent was removed under vacuum whereupon crystallization occured. The crystals (2 g.) were collected and recrystallized from water ml.) to yield transparent colorless needles, M. Pt. 260-262.

The same compound was obtained when 3,4-diamina- S-rnethylthio-1,2,4,-triazole (2 g.) and ethyl pyruvate (2 ml.) were reacted together in refluxing acetic acid (30 ml.) for 4 hours. The product was precipitated by adding ether (300 ml.) and recrystallized from water to give transparent colorless needles (1.3 g.), M. Pt. 260262.

The infrared absorption spectra of both products were identical. The 3,4-diamino-5-methylthio-1,2,4-triazole was prepared as described by Hoggarth, J. Chem. Soc., 1952, 4819.

The product was tested in the same Way as the product of Example 1. The following table shows the results obtained using 0.5 g. product per 1 /2 mols of silver iodobromide.

Initial Test After 14 days at 120 F.

Fog density Rel. log speed Fog density Rel. log speed Control...

. 39 Test 0 EXAMPLE 4 Preparation of 3,5 dimethyl-6-hydroxy1,2,3a,4,7-pentaazaindene Initial Test After 14 days at 120 F.

Fog density Rel. log speed Fog density Rel. log speed Control... 0. 10 5. O4 0. 39 4. 96 Test 0. 04 4. 87 0. 04 4. 95

EXAMPLE 5 Preparation of 3-ethyl-6-hydroxy-S-methyl-1,2,3a,4,7-

penta-azaindene 3,4-diamino-5-ethyl-1,2,4-triazole (12.4 g.) and ethyl pyruvate (13 g.) were reacted together in refluxing glacial acetic acid (25 ml.) for 2 /2 hours. The reaction mixture, after cooling, was poured into ether (500 ml.) and the precipitate collected (10 g.). Recrystallization 5 from ethanol yielded colorless plates (3 g.), M. Pt. 186 C.

The product was tested in the same way as the product from Example 4. The following table gives the results obtained Initial Test After 14 days at 120 F.

Fog density Rel. log speed Fog density Rel. 10g speed Control... Test EXAMPLE 6 Preparation of 3-benzylthio-6-hydroxy-5-methyl-1,2,321, 4,7-penta-a2aindene Initial Test After 14 days at 120 F.

Fog density Rel. log speed Fog density Rel. log speed Coutrol-- 0.12 5. 03 0. 45 s. 10 Test 0. 05 4. 76 0. 04 4. s3

EXAMPLE 7 Preparation of 6-hydroxy-1,2,3a,4,7-penta-azaindene 3,4-diamino-1,2,4-triazole (4 g.) and ethyl glyoxylate (5 ml. crude) were reacted together in refluxing glacial acetic acid (10 ml.) for 1 /2 hours. On cooling the reaction mixture the product crystallized out of solution and was filtered 01f. Recrystallization from ethanol (500 ml.) yielded colorless needles (2.8 g.) M. Pt. 27 l272 C. dec.

The same product was obtained when 3,4-diamino- 1,2,4-triazole hydrochloride (13.5 g.), pyridine (10 ml.) and ethyl diethoxyacetate (17.6 g. crude) were reacted together in refluxing glacial acetic acid (100 ml.) for 2 /2 hours. The acetic acid was then distilled off under reduced pressure. The residue remaining was triturated twice with ether and once with ethanol (50 ml.) to yield a solid (4.5 g.) M. Pt. 262266 C. Recrystallization from ethanol yielded colorless needles, M. Pt. 271-272 C. dec..

The same product was obtained when to 3,4-diamino- 1,2,4-tri-azole (2.5 g.) dissolved in acetic acid (10 ml.) and water (20 ml.) was added glyoxylic acid hydrate (3.5 g.) dissolved in water (10 ml.). The resulting solution was heated at 75 C. for minutes. On cooling crystals of the condensation product (1 g.) were filtered off. Reheating produced a further crop. The condensation product (0.9 g.) was then suspended in glacial acetic acid (5 ml.) and heated under reflux whereupon the solid dissolved Within 10 minutes. After a further 10 minutes refluxing, the mixture was cooled and ethanol (5 ml.) added. After standing at C. for /2 hour the cyclized product was filtered off, M. Pt. 266268 C. dec.

The infrared absorption of spectra of all three products showed them to be identical.

The product was tested in the same way as the product from Example 4. The following table gives the results obtained.

Contro1 Test 4 Tst 6 EXAMPLE 8 Preparation of 6-hydroxy-3-methylthio-1,2,3a,4,7-pentaazaindene 3,4-diamino-5-methylthio-l,2,4 triazole (2.9 g.) and ethyl glyoxylate (3 g. crude) were reacted together in refluxing glacial acetic acid for 4 hours. On cooling the reaction mixture the product crystallized out of solution and was filtered ofi. Recrystallization from 2-methoxyethanol (250 ml.) yielded pale yellow needles (2.1 g.), M. Pt. 280-290 C. dec.

The product was tested in the same way as the product from Example 4. The following table gives the results obtained.

Initial Test After 14 days at 120 F.

Fog density Rel. log speed Fog density Rel. log speed ontrol EXAMPLE 9 Preparation of 3-benzylthio-6-hydroxy-1,2,3a,4,7-pentaazaindene 3,4 diamino 5 benzylthio 1,2,4 triazole (9 g.) and ethyl glyoxylate (6 ml. crude) were reacted together in refluxing glacial acetic acid (30 ml.) for 3 hours. On cooling the reaction mixture the product crystallized out of solution and was filtered ofi. Recrystallization from ethanol (500 ml.) yielded colorless plates (2 g.) M. Pt. 230 C.

The product was tested in the same Way as the product from Example 4. The following table gives the results obtained.

Initial Test After 14 days at 120 F.

Fog density Rel. log speed Fog density Rel. 10g speed EXAMPLE 10 Preparation of 6-hydroxy-3-methyl-l,2,3a,4,7-pentaazaindene 3,4 diamino 5 methyl 1,2,4 triazole (4.5 g.) and ethyl glyoxylate (6 ml. crude) were reacted together in refluxing glacial acetic acid (10 ml.) for 1 hours. Ethanol (30 ml.) was then added to the reaction mixture. After standing at 2 0 C. for hour the product (4 g.) was filtered off. Recrystallization from ethanol (500 ml.) yielded long colorless needles (2 g.) M. Pt. 275-280 C.

EXAMPLE 11 Preparation of 3-ethyl-6-hydroxy-5-phenyl-1,2,3a,4,7-

penta-azaindene 3,4 diamino-S-ethyl-l,2,4-triaz0le (3.2 g.) and ethyl phenylglyoxylate (4.5 g.) were reacted together in refluxing glacial acetic acid (3.2 ml.) for 3 4 hours. The product crystallized out during the course of thereaction. The reaction mixture was then dissolved in boiling ethanol (250 ml.) and decolorizing charcoal added. After filteration, the solution deposited a yellow crystalline powder (3.1 g.), M. Pt. 226235 C. Recrystallization from ethanol yielded fiuffy needles (1.6 g.), M. Pt. 226 C.

The product was tested in the same way as the product from Example 1. The following table gives the results obtained using 0.16 g. compound per 1% moles silver halide.

Control Test '7 EXAMPLE 12 Preparation of 6-hydroxy-3 -methyl--phenyl-1,2,3a,4,7- penta-azaindene 3,4 diamino 5 methyl-1,2,4-triazole (4.5 g.) and ethyl phenylglyoxylate (7.2 g.) were reacted together in refluxing glacial acetic acid ml.) for 2 hours. The product crystallized out during the course of the reaction. Ethanol (30 ml.) was then added to the reaction mixture. After standing at 20 C. for hour, product (3 g.) was filtered ofl. Recrystallization from ethanol (300 ml.) yielded pale yellow long needles (2 g.), M. Pt. 310-313" C. dec.

EXAMPLE 13 Preparation of 6-hydroxy-5-phenyl-1,2,3a,4,7-pentaazaindene 3,4 diamino 1,2,4 triazole (4 g.) and ethyl phenylglyoxylate (7.2 g.) were reacted together in refluxing glacial acetic acid (10 ml.) for 3 hours. The product crystallized out during the course of the reaction. Ethanol (30 ml.) was then added to the reaction mixture. After standing at 20 C. for /2 hour, the product (4 g.) was filtered off. Recrystallization from ethanol (200 ml.) yielded pale yellow needles (2 g.), M. Pt. 274277 C. dec.

EXAMPLE 14 Preparation of 6-hydroxy-3-mercapto-5-phenyl-1,2,3a,4,7- penta-azaindene Sodium (7.7 g.) was dissolved in ethanol (1400 ml.) and to the resulting solution 3-hydrazino-5-hydroxy-6- phenyl-1,2,4-triazine (73 g.) and carbon disulphite (35 ml.)were added. The mixture was refluxed for 2 hours, during which time hydrogen sulphide was evolved and a crystalline solid formed. The reaction mixture was filtered hot to yield solid (A) and filtrate (AF). Solid (A) (53 g.) was recrystallized twice from methanol and the resulting solid (18 g.) added to water (300 ml.). After filtering off an insoluble material the filtrate was acidified with concentrated hydrochloric acid to yield a yellow crystalline solid (8.5 g.). Recrystallization of the latter from methanol (600 ml.) yielded bright yellow crystals, M. Pt. 293294 C.

EXAMPLE 15 Preparation of 6-hydroxy-3-methy1thio-5-phenyl- 1,2,3 a,4,7-penta-azaindene 3,4 diamino 5 methylthio 1,2,4 triazole (1.45 g.) and ethyl phenylglyoxylate (1.75 ml.) were reacted together in refluxing glacial acetic acid (2 ml.) for 2 hours. Ether was then added to the reaction mixture and after decanting oil the ethereal layer the remaining solid was three times recrystallized from ethanol to yield offwhite flufly needles (0.25 g.), M. Pt. 249-254 C.

The same product was obtained when 6-hydroxy-3-mercapto 5-phenyl-l,2,3a,4,7-penta-azaindene (2.5 g.) dissolved in a solution of sodium hydroxide (0.4 g.) in water (54 ml.) was shaken for one hour with methyl iodide (1.5 ml.). The resulting solid was filtered off and upon recrystallization once from ethanol yielded oil-white fluify needles (0.5 g.).

The infrared absorption spectra of both products showed them to be identical in structure.

EXAMPLE 16 Preparation of 3,5-dimethyl-6-hydroxy 1,2,3a,4,7-penta-azaindene 3-acethydrazin0-5-hydroxy-fi-rnethyl-1,2,4 triazine (1.1 g.) was boiled under reflux with glacial acetic acid (30 ml.) for 2 /2 hours. The initially insoluble starting material gradually dissolved until only a trace of insoluble material remained. The reaction mixture was then cooled and filtered. The clear filtrate was evaporated to dryness under reduced pressure and the residue remaining was recrystallized from ethanol (30 ml.) to yield the product as colorless needles (0.6 g.) M. Pt. 245246 C.

The same product Was obtained when 3-acethyd-razino- 5-hydroxy-6-methyl-1,2,4-triazine (1.0 g.) was heated under reduced pressure in a silicone fluid bath at 250- 265 C. for 5 mins. Recrystallization from ethanol (20 ml.) yielded the product as off-white needles (0.2 g.) M. Pt. 247-248 C.

The same product was obtained when 3-hydIazino-5- hydroxy-6-methyl-1,2,4-triazine (1.0 g.) was heated under reflux with an excess of glacial acetic acid (30 ml.) for 2 /2 hours. The initially formed and precipitated 3-acethydrazino-S-hydroxy-G-methyl-1,2,4-triazine gradually dissolved during the course of the reaction. At the end of the reaction time the acetic acid was removed by distillation under reduced pressure. The residue remaining was recrystallized from ethanol (30 ml.) to yield colorless needles (0.6 g.) M. Pt. 245-246 C.

The infrared absorption spectra and ultraviolet absorption spectra of the above products showed them to be identical in structure to the product described in Example 4.

EXAMPLE 17 Preparation of the intermediate 3-acethydrazino-5-hydroxy 6-methyl-1,2,4-triazine 3-methy1thio-5-hydroxy-6-methyl-1,2,4-triazine (7.8 g.) and acethydrazide (4.0 g.) were reacted together in refluxing Z-methoxyethanol (25 ml.) for /2 hour. The product crystallized out of solution during the course of the reaction. The hot reaction mixture was then poured into hot ethanol (50 ml.) and filtered hot to yield colorless crystals (3.0 g.), M. Pt. 241 C.

3-hydrazino-5-hydroxy-6-methyl-1,2,4-triazine (10 g.) was boiled under reflux with glacial acetic acid (40 ml.) for 6 minutes. The product crystallized out of solution during the course of the reaction. The hot reaction mixture was then poured into ethanol (250 ml.) and the solids filtered off, boiled with ethanol (250 ml.), cooled and filtered to yield colorless crystals (5.5 g.), M. Pt. 235237 C.

The infrared absorption spectra of both products showed them to be identical.

We claim as our invention:

1. A penta-azaindene compound of the formula:

bit-0:2

where R is a hydrogen atom or a lower alkyl, phenyl, benzyl, mercapto, lower alkyl mercapto or benzyl mercapto group and R is a hydrogen atom or a lower alkyl, phenyl or benzyl group, with the exception of the case where, simultaneously R is a hydrogen atom and R is a methyl group.

2. 5-methyl-6-hydroxy-1,2,3a,4,7-penta-azaindene.

3. 6 hydroxy 3 mercapto-S-methyl-1,2,3a,4,7-pentaazaindene.

4. 6-hydroxy-3-methylthio 5 methyl-1,2,3a,4,7-pentaazaindene.

5. 3,5-dimethyl-6-hydroxy-l,2,3a,4,7-penta-azaindene.

6. 3-ethyl 6 hydroxy 5 methyl 1,2,3a,4,7 pentaazaindene. I

7. 3-benzylthio 6 hydroxy-S-methyl-l,2,3a,4,7-pentaazaindene.

8. 6-hydroxy-1,2,3a,4,7+penta-azaindene. I

9. 6-hydroxy-3-methylthio-1,2,3a,4,7-penta-azaindene. 

